A conversation with physical oceanographer Joe Pedlosky

On a softball field, Joe Pedlosky plays a respectable first base, sporting a baseball cap that sprouts Hermes-like wings. But in the field of physical oceanography, he is a bona fide star. In January 2005, the WHOI senior scientist was awarded the prestigious Sverdrup Gold Medal of the American Meteorological Society, given to researchers who make outstanding contributions to the knowledge of interactions between the oceans and the atmosphere. Not bad for an oceanographer who has never gone on a research cruise.

At cocktail parties or around the Thanksgiving table, how do you answer the question: “So, what do you do?”

I try to explain the motion of the ocean.

Physical oceanography is the quest to discover and understand how the ocean is moving, over space and time, on a wide range of scales: From the moon-driven tides to large waves that span the entire planet and are only visible in satellite data; from so-called rapid surface gravity waves, like the recent tsunami to internal waves—which are heaving motions along layers within the oceans—to the persistent general circulation of currents and gyres. All the physics needed to unravel this wide variety of motion can be described using the same basic mathematical/physical laws that Newton used to describe the motion of the planets in their orbits.

So, this makes me a theoretician. I never go to sea—except conceptually. I work with paper and pencil and computer.

What encouraged you to pursue this line of work?

In 1960 I was an aeronautical engineering student in love with aerodynamics—the dynamics of flowing air. I answered an advertisement for the now venerable WHOI Geophysical Fluid Dynamics summer seminar program, which had just started the year before. It offered the promise of a summer on the Cape while doing fluid dynamics, two things I greatly enjoyed. I had no intention of becoming an oceanographer, and I believe I said so on my application. They took me anyway.

I had a splendid research experience that summer with Melvin Stern, who is not only a brilliant scientist, but was a kind and encouraging mentor to me. He made me realize that fluid mechanics was even richer than what I had been experiencing in my engineering courses. Soon after, I fell under the inspiring influence of Professor Jule Charney in the Meteorology Department at MIT, with whom I did my Ph.D. thesis.

I remember one hair-raising ride down to Woods Hole from MIT. Jule was driving, paying no attention to the traffic, and explaining to me to me how he felt connected—through a generation-spanning series of his mentors, and their mentors, and the mentors of those mentors—all the way back to the great 19th-century physicists who were his heroes. This was an invitation for me to feel similarly connected to the communal scientific effort since the Enlightenment to understand our world.

You earned the Sverdrup medal for your “theories of the general circulation and baroclinic instability.” Would you translate?

The general circulation of the ocean is a massive and majestic phenomenon. The mass of water in the Gulf Stream that rushes past Cape Hatteras every second is greater than the weight of all the people in China! This grand sweeping circulation of the ocean is driven by an ensemble of physical causes—like the action of the wind on the ocean surface or the uneven heating and cooling of the ocean by the sun.

These physical forces lead to variations in temperature and densities within the ocean and atmosphere—a situation that is inherently unstable. A broomstick balanced upside down, for example, is in an unstable equilibrium position. If it is even slightly disturbed, it will quickly tumble. Potential energy is converted to kinetic energy.

Similarly, even the smallest disturbances in the Gulf Stream in the ocean, or the Jet Stream in the atmosphere, will release waves, which bring us our weather in the atmosphere and result in eddies and meanders in the ocean. This is the so-called butterfly effect. The theory that describes these phenomena is called baroclinic instability.

At the age of 34, you were a full professor at the University of Chicago. Why did you give that up to work at WHOI?

I loved the University of Chicago. I left it with great sadness, but I felt at the time that the general intellectual stimulation of the university was not enough to balance the opportunity to interact with so many truly fine researchers in my own scientific area of interest here in Woods Hole.

Like all creative efforts, an oceanographer’s work is often solitary. Ideas come at all times; realizations of error come unbidden in the small hours; and brooding over an unsolved problem has no schedule. Research is an intensely personal activity, but it is also a deeply human one: Collaborations and interactions are an indispensable stimulant—a chance remark over lunch, a criticism at coffee time, supportive enthusiasm at a seminar.

Though I stick close to my desk and never go to sea, I work in concert with people who do go to sea. They collect observations against which my theories are tested, and which also suggest the need for new theories. I have learned much from my colleagues.

All that said, I would not have given up the security of salary support at Chicago if I hadn’t received similar support at WHOI. The tension and pressures of constantly having to raise one’s own salary by submitting research funding proposals for competitive review is a necessary evil, but it does not in itself sharpen the quality of one’s work. In my experience, scientists on “hard money” work no less hard and are no less creative. Stable support is essential: It permits long lines of thought or experimentation on hard, risky problems.

What do you hope to achieve with your work?

I have hoped to contribute to the understanding of the inner workings of the ocean and the atmosphere.

But an equally honest answer is that the challenge and the satisfaction for the theoretician is to see, unfolding on the page before him, a mathematical consequence of basic laws of physics that tell us, for example, “Well, yes, there should be an Equatorial Undercurrent, and this should be its characteristic width, depth, and speed, and this is why it is there.” You can understand the enormous personal satisfaction of seeing that explanation unfold—first to you alone. It must be like the satisfaction artists feel in seeing their paintings capture the essence of a person or a landscape.

You’ve described your scientific endeavors in terms of journeys, history, and art. Have you pursued these in nonscientific ways?

My family and I have spent parts of many years now in Italy. There is an elegance to Italian cuisine, grace in its people, and beauty in its art—characteristics that all theoreticians aspire to in their work.

Italy for me is largely Venice, which, after all, is a city that lives in water. Water and its motion and its effects of light are everywhere. I started playing with rainwater in the gutters and alleyway puddles of Paterson, New Jersey, as a boy, and now I get to enjoy the canals of Venice. That, certainly, is some progress.

I also play the clarinet, which brings to mind the terribly destructive saying that “anything worth doing is worth doing well.” It simply isn’t true. I will never be a very good clarinetist, having started late in life, when I was 40. But the pleasure of playing is very important to me, and if it does not meet someone else’s standard, I choose not to worry about that. Mozart hasn’t complained, or can’t, and fooling around with jazz is my democratic right.

And then there’s baseball. Tell us about your winged cap.

Shortly after I arrived in Woods Hole, two close friends presented me with my winged hat—a tribute, I think, to my slowness on the base paths. Sometimes I meet people from other teams who recognize me only after I introduce myself as the man with the winged hat.

Baseball is surely a scientist’s game. After all, a great batter mostly fails; the very good ones fail two-thirds of the time, and that is a great lesson. If you try to do something very hard like hit a baseball or explain the circulation of the ocean, be prepared to fail, and often.

Images

"I try to explain the motion of the ocean," says WHOI physical oceanographer Joe Pedlosky, who was awarded the prestigious Sverdrup Gold Medal of the American Meteorological Society in 2005 for his theories explaining the inner workings of the ocean and the atmosphere. (Photo by Tom Kleindinst, WHOI)

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